Field of the Invention
The present invention relates to a Group III nitride semiconductor light-emitting device and a production method therefor, more specifically, to a method for producing a Group III nitride semiconductor light-emitting device having pits.
Background Art
A Group III nitride semiconductor light-emitting device comprises a light-emitting layer which emits light through recombination of electrons and holes, an n-type semiconductor layer, and a p-type semiconductor layer. When producing the Group III nitride semiconductor light-emitting device, a semiconductor layer is epitaxially grown on a substrate. In this case, threading dislocation occurs in the semiconductor layer due to lattice mismatch between the substrate and the semiconductor layer. In the threading dislocation, non-radiative recombination of electrons and holes occurs. Non-radiative recombination refers to a recombination of electrons and holes which generates not light but heat. Therefore, electrons existing in the vicinity of the threading dislocation may cause non-radiative recombination at the threading dislocation. The more frequently non-radiative recombination occurs, the more heat the semiconductor light-emitting device generates. The emission efficiency of the semiconductor light-emitting device is decreased by the amount of the generated heat.
Accordingly, the techniques have been developed to suppress non-radiative recombination in the threading dislocation. For example, Japanese Translation of PCT International Application Publication No. 2008-539585 discloses that pits originated from threading dislocation are generated from the superlattice structure 16 or the GaN layer 12 (refer to paragraphs [0059], [0073], and FIGS. 1 and 2). The superlattice structure 16 has an InGaN/GaN structure. Existence of such pits improves the luminance or the electrostatic discharge resistance of light-emitting device (refer to paragraphs [0042] to [0043]).
In this way, the light output of the semiconductor light-emitting device has been improved through research and development. However, to improve the light output, it is required that electrons and holes are not further captured by threading dislocation.